Office chairs conventionally employ a seat assembly swivelly supported on a pedestal-type base. For this purpose, the seat assembly normally has a threaded spindle associated therewith, which spindle coacts with a nut arrangement associated with the base. This permits conventional swivelling of the seat assembly when the chair is occupied, and also permits the height of the seat assembly to be suitably adjusted in response to rotation of the seat assembly relative to the base. Such constructions, of many different types, are well known in the chair industry.
In view of the rather unsightly appearance created by the spindle and the related adjustment hardware, commonly referred to compositely as the spindle assembly, the chair industry has utilized various types of shrouds or closures for improving the esthetics of the chair, and providing for safety of operating personnel by restricting or limiting access to the spindle assembly. One cover which has been extensively utilized, although with less than satisfactory results, is an elongated boot (such as a bellows) constructed from an elastic rubberlike material, such as a plastics material. When such a boot or bellows is used for enclosing the spindle assembly, the lower end is normally anchored to the base so as to maintain the boot in a nonrotatable condition. However, due to the required rotation and swivelling movement of the seat assembly, the upper end of the boot is normally not supported on or connected to the seat assembly, but rather is normally solely urged into abutting engagement with the lower side of the seat assembly due to the springlike effect of the boot as created by its natural resiliency. While this arrangement does initially operate satisfactorily, nevertheless it has been discovered that when the boot is subjected to some standard usage conditions, the boot undergoes what is commonly referred to as inelastic creep. That is, the boot loses some of its elasticity or resiliency, and hence no longer sufficiently resiliently expands so as to urge the top end of the boot into its proper position when the chair seat is adjusted into or adjacent its uppermost limit. For example, when a chair seat is utilized adjacent its lowermost position for substantial periods of time, this continual compression of the boot causes inelastic creep, such that when the chair seat is again returned into or adjacent its uppermost adjusted position, the boot is unable to sufficiently elastically expand so that the upper end of the boot is thus spaced downwardly or sags relative to the chair seat. This obviously destroys the appearance of the chair. Because of this problem, many chair manufacturers have abandoned the use of boots and instead have adopted telescopic tube arrangements for enclosing the spindle assembly, although even these arrangements possess other features which are considered less desirable than boots.
Accordingly, it is an object of this invention to provide an improved arrangement for supporting the upper end of a boot relative to the chair seat, whereby the boot as used in surrounding relationship to the spindle assembly is positively extended whenever the chair seat is adjusted upwardly so as to insure that the boot effectively encloses the spindle assembly. This improved arrangement hence effectively overcomes the problems and disadvantages noted above.
In this invention, an extendible and contractible boot, such as a bellows, is constructed of a rubberlike material and is disposed in surrounding relationship to the spindle assembly. The lower collar or convolution of the boot is anchored to the pedestal associated with the chair base. The upper collar or convolution of the boot is mounted to and supported on the seat assembly by a retainer arrangement which prevents vertical separation between the boot and seat assembly but permits relative rotation therebetween. This retainer arrangement employs a bearing ring, preferably of a split construction, which is snugly and resiliently seated within the upper collar or convolution of the boot. A washerlike retainer plate is secured relative to the spindle and has an outer annular flange which is bearingly but rotatably supported on and by the bearing ring. The bearing ring has suitable locking tabs which overlap the upper edges of the annular flange for axially securing the bearing ring, and hence the boot, to the retainer plate. However, the retainer plate, and hence the chair seat, can rotate relative to the bearing ring.
Thus, one objective of this invention is the provision of an arrangement which axially secures the upper end of the boot to the seat assembly while simultaneously permitting relative rotation therebetween. Another objective is the provision of an arrangement, as aforesaid, which is structurally simple, economical to manufacture, simple to assemble, durable in operation, easily and simply disassembled and reassembled without requiring elaborate tools or skills, and does not affect or interfere with the desired esthetics of the chair.
Other objects and purposes of the invention will be apparent to persons familiar with this technology upon reading the following specification and inspecting the accompanying drawings.